Magnetomotive agitator for molten metal baths or the like



Dec. 13, 1960 MAGNETOMOTIVE Fig.2.

E; A. HANFF 2,964,581

AG ITATOR FOR MOLTEN METAL BATHS OR THE LIKE Filed Feb. 24, 1959 INVENTOR.

Edward A. Hanff ZMAW MAGNETOMOTIVE AGITATOR FOR MOLTE I. METAL BATHS OR THE LIKE Edward A. Hanlf, Wilkinsburg, Pa.,- assign'or to Swindell- Dressler Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 24, 1959, Ser. No. 795,011 6 Claims. or. 13-26 This invention relates to a magnetomotive agitator for stirring baths; of molten substances such as metal and, more particularly, is an additional construction to achieve objects and advantages stated in my copending application Serial'No. 642,493 filed February 26, 1957, now Patent No. 2,875,261 issued February 24, 1959.

In the illustrated embodiment of my present construction, provision-is made for alternating current excitation of an inductor with flexible control of the armature current to set up a selectively rotatableflux field for successive linkage with stator elements of such inductor, thereby providing an alternating current output of effective valu es which preferably are rectified before being amplified and impressed in progressive fashion uponl'stationary pole coils of an agitatorbed to provide stirring ofsuch amolten metal bath or the like. Other objects, features and advantages of this invention will be apparent fronrthe following description, and accompanying draw,- ings, in which l Figure lis a schematic view of oneform of my new construction; and r Figure 2is a view of an inductor portion thereof taken along lineII-JI of Figure 1.. Y In the illustrated embodiment, a bath 10 of molten material like steel is contained in a refractory or .refraca torylined container 11 which is underlain by a stationary inductor bed 12 having transversely and upwardly extendingpoles 13 closely adjacent to the underside of container llfsuchbed being preferably made of laminated magnetic material with the bottom of the bed yoking the respectivepoles 13. Magnetic flux forces are generated successively at" the poles 13 by unidirectional current pass ing through respective pole coils 14 to provide recurrent waves of repulsion force from left to right as viewed in Figure 1 to agitate or stir the molten bath 10. Such direc-. tion of-impulse wave progression may be reversed by re arranging the respective electric connections shown in Figure l.

Selective relatively high current and relatively low impulse frequency conditions most generally to be preferred in the stirring of fluent substances may be obtained at an amplified. level byfthe use of an amplifiengenerator 16 for eachof the'coils 14. The amplifier-generators 16 maybe connected by a common shaft 17 to, for example, an A.C. drive motor 18 which may include speed variation mechanism. Each of the amplifier circuits, as shown, includes a .winding 19, which as shown is a series field winding for its respective amplifier 16, in series with coil :14. Further, a shunt 20 connected across the respective windings 19 may also be included, if desired, for'selective adjustment of the unidirectional current impulses successively flowing in each' of such coils 14. Brushes in each generator 16 are in engagement with a commutator connected. to the winding on the armature of the respective-generator 16 during rotation thereof by the shaft "17 at the selected speed. If'desired, the amplifiers 16 may be independently driven as, for example, when a lesser current step-up may be wished for the poles 13 and 2,964,581 Patented Dec. 13, 1960 ice coils 14 at the ends of bed 12 as where the bath 10 is sufficiently shallower at such ends. The output of the generators 16 provides a magnification of the unidirectional voltage and current of a pulsating nature impressed across a main field coil 21 in each of the generators 16 in a selected sequence and at a selected frequency by the rectified output impulses of an inductor 22 of analternator-type. V

Inductor 22 is provided with an angularly spaced plurality of stators 23 preferably made of laminated U-shaped magnetic material in the core portion 24 thereof. Each stator core 24 is linked by at least one induction coil 25 connected to a respective rectifier 26 which, as shown, is a full wave rectifier, the output of which supplies unidirectional current to the field coils 21 as aforesaid to create the flux cut by the rotation of the respective armature instant case is indicated by arrow 28. Rotor 27 is pro vided with a U-shaped coreportion 29 preferably of laminated magnetic material which is excited byat least one rotor coil 30 through the window of which the-yoke of rotor core 29 passes. Rotor arms 31 rigidly connect rotor. 27 to a shaft 32 which is turned at the selected stirring impulse frequency speed desired by a drive motor 33 through a speed reducer mechanism 34. The efliciency of inductor 22 is aided by having the rotor and stator cores virtually form an almost complete magnetic fiux path of low reluctance as shown in the upper part of Figure 2. Twice the frequency for the same speed of rotationof shaft 32 maybe obtained, if desired, by providing a secondfrotor 27a corresponding to rotor 27 but 180 re-j moved therefrom as shown by the dotted outline thereof in Figure 1.

The ends of ,coil30 may have leads thereto passing out through an opening 35 for respective fixedconnection to slip rings 36 secured sov as to rotate with shaft 32. A brush 37 rides on each of the slip rings to conduct the alternating exciting current to coil 30, which exc'itingcurrentisflexibly controllable by a regulator 38. j g

' The respective brushes 37 are connected across a secondary winding 39 of a step-down transformer having a primary winding 40 supplied by single phase alternating electric current power. One of the conductors 41 of winding through coil 44 is adjustable by virtue of a variable resistance rheostat 45. The respective wires 46 to rheostat 45 and coil 44 are connected to a suitable direct electric current supply available in the plant where the device is used. Other regulators may be used to control the magnitude of the A.C. exciting current to the rotor 27.

'In operation, rotor 27 is excited by the desired current flow through coil 30 responsive to the characteristicsof transformer 39- -40 and the setting of rheostat 45 whereby for a lower resistance in the circuit of lines 46, a greater current will flow in coil 44 and a greater flux density will be impressed upon core 43 thereby, which in turn means that there will be less counter electromotive force induced by virtue of a flow of current through wire 41 and the compound coil 42 so that more current will flow through coil 30 generating a more powerful magnetic flux force in the rotor core 29. As rotor 27 moves into linking engagement with a stator 23, its alternating output in terms of voltage and current induced in the stator coil 25 in linkage relation with the rotor at that moment will be a function of the turn ratio of the respective coils 30 and 25. Moreover, the interval between output impulses 3 from the given stator coils 25 will depend upon the speed of rotation of shaft 32. Each such stator coil 25 produces alternating current impulses which by means of the respective above-mentioned rectifier 26 are converted to unidirectional impulses which will excite the field coil 21 connected thereto in the predetermined sequence and with the same interval between impulses. Therise and fall of the flux fields in timed relation produced by each set of the respective coils 25 and 21 in turn are directly reflected in amplified form and at the correct selected frequency and magnitude in terms of voltage and current successively at the poles 13 from which emanate the successive flux fields for the predetermined agitation of bath 10. It is thus clear that despite a change in the nature of the molten material to undergo magnetic stirring, or of the container 11, or of other factors affecting induction stirring, my new construction may be readily adjusted and regulated to achieve optimum operation despite the presence of such new factors. 7

Various modifications may be made in aspects of the illustrated embodiment and other embodiments of my invention disclosed herein may be provided without departing from the spirit of my invention or the scope of the appended claims.

I claim: 7

1. In a magnetomotive agitator for a molten metal bath or the like, apparatus comprising, in combination, a stirring bed made of a magnetic material, a plurality of progressively spaced pole pieces in said bed, a plurality of pole coils respectively linked with said pole pieces to provide a progression in a selected direction of unidirectional magnetic flux force impulses in said pole pieces of predetermined magnitude and frequency, an iuductor having a rotor and angularly spaced stators, said rotor and each of said stators having a U-shaped core to form a substantially complete relatively low reluctance magnetic core when said rotor is substantially opposite to oneof said stators, a rotor coil on said rotor core and a stator coil on each of said stator cores, means for revolving said rotor at a selected speed, means for exciting said rotor, by means of alternating electric current,,saturable core means for regulating the, magnitude'of said rotor excitation, means for rectifying the output of each of said stator coils, independently rotatable means to magnify the rectified output of each of said stator coils, and means for conducting said magnified rectified output of each stator coil to a particular pole coil for the successive 611613 gization thereof.

2. In a magnetomotive agitator for a molten metal bath or the like, apparatus comprising, in combination, a. stirring bed having a plurality of spaced pole pieces, a pluralityof pole coils respectively linked to said pole pieces to provide a progression of unidirectional magnetic flux force impulses of predetermined magnitude and frequency, an inductor having a rotor and angularly spaced stators, a rotor coil on said rotor core and a stator coil on each of said stator cores, means for revolving said rotor at a selected speed, means for exciting said rotor by means of alternating electric current, means for regulating the magnitude of said rotor excitation, means for rectifying and amplifying the output of each of said stator coils, and means for conducting said amplified rectified output of each stator coil to a particular pole coil for the successive energization thereof.

3. In a magnetomotive agitator for a molten metal bath or the like, apparatus comprising, in combination, a magneto stirring bed having upwardly and transversely extending poles placed in juxtaposition to said bath, coil. means respectively linked with said poles to provide unidirectional magnetic flux force impulses of predetermined magnitude and frequency, an inductor having angularly disposed stators with U-shaped cores and stator coils respectively linked thereto, a rotor in said inductor having 4 i a U-shaped core and a rotor coil linked thereto, means for driving said rotor at a selected speed, saidrotor'and respective stator coils forming a substantially complete magnetic path when the same are in substantial radial registry, means for providing said rotor coil with alternating electric current excitation, adjustable saturable core means for regulating the magnitude of the exciting current flowing through said rotor coil, sequential rectifying means for the output of each of said stator coils and sequential means to amplifyv the rectified output of each of said stator coils, said amplified rectified output of each of said stator coils being the input to a respective and successive one of said coil means. V

4. In a magnetomotive agitator for a molten metal bath or the like, apparatus comprising, in combination, a magnetic stirring bed, a plurality of spaced pole pieces on said bed, a plurality of pole coils respectively linked with saidpole pieces to provide a progression of unidirectional magnetic flux force impulses in said pole pieces of predetermined magnitude and frequency, an inductor having a rotor and angularly disposed stators, mutual induction means respectively mounted on said rotor and said stators, means for revolving said rotor at a selected speed, means for exciting said rotor with alternating current, means for regulating the magnitude of said excitation, means for rectifying the output from said inductor caused by the transformation linkage of said rotor successively with said stators and means to magnify said rectified output and connect it to said pole coils respectively and successively.

5. In a magnetomotive stirrer for fluent substances, apparatus comprising, in combination, an inductor having a rotor and a stator class of members, means for im-' pressing alternating current excitation upon one of said class of members to provide an alternating output in the other thereof, said stator class of members being angularly spaced, means for rotating said rotor class'of members to provide a predetermined frequency and magnitude of impulses in said output, means for converting said alternating impulses into unidirectional impulses of said frequency, means for impressing said unidirectional impulses upon an amplifying means tomagnify the same and means for transmitting the amplified'unidirectional impulses to spaced magnetic coil and coremembers to provide a succession of temporally and spatially'spaced unidirectional magnetic flux forces to stirsaid fluent substances. r

6. In a magnetomotive agitator for a molten metal bath or the like, apparatus comprising, in combination, a stirring bed made of a magnetic material, a plurality of progressively spaced pole pieces in said bed, a plurality of pole coils respectively linked with said pole pieces to provide a progression in a selected direction of unidirectional magnetic flux force impulses insaid pole pieces of predetermined magnitude and frequency, an inductor having a rotor and angularly spaced stators, said rotor and each of said stators having a U-shaped core to form a substantially complete relatively .low reluctance magnetic core when said rotor is substantially opposite to one of said stators, a rotor coil on said rotor'core and a stator coil on each of said stator cores, means for revolving said. rotor at a selected speed, means for exciting said rotor by means of alternating electric current, means for regulating the magnitude of said rotor excita? tion, means for rectifying the output of each of said stator coils, and means for conducting said rectified output of each stator coil to a particular pole coil for the. successive energization thereof.

References Cited in the file of this patent UNITED STATES PATENTS 

